This invention relates to a high speed shuttle conveyor for transferring an article carrier along a predetermined path, e.g. from one work area to another work area. The shuttle conveyor can increase the overall speed of the conveyor system while permitting each article conveyor to remain at any given work area for a relatively long period of time. The invention has particular application for shifting heavy automobile bodies along a conveyor path during automobile assembly operations.
Shuttle conveyors are known in the prior art. U.S. Pat. No. 5,322,156 shows a shuttle conveyor system comprising plural pairs of drive belts that overlap in the direction of belt travel, whereby an automobile body can be transferred from one pair of belts to another pair. The belts apparently slide on flat support surfaces in order to preclude buckling of the belts under the heavy loads imposed by the automobile body.
U.S. Pat. No. 3,180,279, to P. Thibault, shows an overhead chain conveyor system having stationary tracks at spaced points for temporarily retaining an article carrier while the conveyor chain continues to move at normal speed.
U.S. Pat. No. 4,669,388 to C. Dehne et al. shows a conveyor system that includes a carriage that can be successively detached from an article carrier and then reattached to the carrier for achieving a variable speed advance of the carrier along the conveying path.
The present invention relates to a high speed shuttle conveyor system that includes overhead belt means designed to move a carriage means rapidly back and forth in a horizontal motion above an article carrier that is supported for guided motion along a separate rail system. The carriage means has detachable connections with the article carrier so that when the carrier is under the control of the carriage means, the carrier is propelled along the rail system at a higher than normal speed.
The overhead belt means is cyclically movable back and forth, whereby the carriage is enabled to propel an article carrier in the forward direction, and to then return to a starting position to pick up another article carrier. A principal aim of the invention is to provide a high speed shuttle system that separates in cyclic fashion without having to remove each article carrier from the support rail. The shuttle system pushes each article carrier while the carrier continues to be supported by the rail.
In the preferred practice of the invention, the shuttle system carriage has a deceleration mechanism that decelerates each carrier to a motionless (or near motionless) condition as the carriage nears the end of its forward travel. The carriage operates at a relatively high speed without generating dangerous uncontrolled accelerations of the article conveyor. The system is designed to safely handle heavy articles, such as automobile bodies weighing in excess of 3 thousand pounds with an article carrier of 4 thousand pounds.
Features of the invention will be apparent from the drawings and accompanying description of an illustrative embodiment of the invention.